The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In the oil production technology based on the use of the hydraulic fracturing methods, the well production is enhanced by injecting proppant granules into fractures made in an oil-bearing formation, in order to fix the position of the fracture walls, thus preventing them from closing. The proppant is injected into fractures by pumping a proppant-containing fracturing fluid under high pressure. It has been experimentally established that a lower apparent density allows a more uniform distribution of the proppant and increases the oil and gas production levels.
In International Publication No. WO 2006/034298, proppant granules are described as coated particles made of an inorganic material which is a mixture of quartz and alumina taken at a ratio of approximately 2.2:5 and having a bulk density less than or approximately equal to 1 g/cm3. This reference also describes an underground formation treatment method, according to which a fracturing fluid is injected into an underground formation, and the fracturing liquid contains inorganic particles consisting of quartz and alumina at a ratio of approximately 2.2:5, and the inorganic material has an apparent density less than or approximately equal to 1 g/cm3.
U.S. Pat. No. 6,582,819 describes composite particles that are based on a binder and a filler and are suitable for use in the hydraulic fracturing technique. The filler may contain two or more different materials. The binder usually consists of a polymeric material, possibly, with cement added. The resulting composite particles have a bulk density varying from 0.5 to 1.30 g/cm3 and can be used as a proppant in the oil and gas production industry, as well as for filtration of water and for production of synthetic grass for sports grounds. The methods of production of the composite particles are also described.
U.S. Pat. No. 6,632,527 also describes composite particles that are based on a binder and a filler and are suitable for use in the hydraulic fracturing technique. The filler is usually a fine mineral substance to which fibrous materials can be added. Apart from the hydraulic fracturing technique, the particles can be used for filtration of water and for production of synthetic grass for sports grounds. Methods of production of the composite particles are also described.
The prior-art proppants show a lack of efficiency in the hydraulic fracturing technique. Accordingly, new proppants and methods of forming proppant materials are needed.